Add lingonberries, cranberry juice and maple syrup to a medium-sized pot. Bring it to a boil, add the chia seeds and then let it simmer for about half an hour. Use a fork or potato masher to mash the lingonberries a bit. It should thicken up a bit, but it will thicken up even more in the fridge. At this point, you can try and adjust the sweetness by adding more maple syrup if you want!
To store it, let it cool off just a bit and fill it in an air-tight glass jar. You can store the jam in the fridge for 3-4 weeks!